While I admire the effort taken in setting a "rube-goldberg" set of software to achieve this, I see 2 major issues with this in the long term:
1. If this gains any popularity, Apple will change the iMessage protocol in such a way that breaks this, which will start a "cat and mouse" game should the maintainer(s) decide to keep this up to date
2. Projects like this encourage Apple to create products inside their sheltered, walled garden and not play nicely with others outside their garden.
Neither of these is a desirable mode of operation in the long term.
I give people several modes to reach me, some of which may incur SMS costs, most of which don't (FB Messenger, Hangouts, SMS). All of them are multiplatform/os. If they don't use one of those 3 methods, then oh well, they didn't really want to reach me. Or they call or email me if they really need to reach me that bad.